Increasing demand in the oil industry has created a need for a high performance synthetic base oils with low volatility and high oxidative stability. Currently, poly-alpha-olefins (PAO) are used as synthetic base oils but costs are high. This has created a demand for a low cost alternative to PAO such as synthetic hydrocarbons with equivalent or better properties. The present invention is based, in part, on the surprising and unexpected discovery that synthetic base oils may be formulated directly into motor oils or fractionated into different viscosity grade oils with properties equivalent to commercial PAO.
Various prior art publications are available relating to poly-alpha-olefin polymers. Reference may be made to U.S. Pat. Nos. 4,668,834, 4,542,199, 5,446,221, 4,704,491, 4,377,720, 4,463,201, 4,769,510, 4,404,344, 5,321,107, 5,151,204, 4,922,046, 4,794,096, 4,668,834, 4,507,515, and 5,324,800. Many of these prior art patents involve polymerization of ethylene or poly-alpha-olefins using a catalyst combination comprising a transition metal complex and an aluminoxane.
The present invention provides polymers of poly-olefins which have a high viscosity index, low pour point, low cold cranking viscosity, high fire point and excellent oxidation stability.